双曲正割脉冲在光纤中传输的非线性效应

Nonlinear effects of hyperbolic secant pulse transmission in fiber

高斯型脉冲在光纤中的传输已有解析解,而对于一些锁模激光器发射的双曲正割脉冲在光纤中的传输特性尚未有解析解。为了研究高功率双曲正割脉冲在单模光纤中的传输特性,文中借助于分步傅里叶方法分析了峰值功率5 000 W的双曲正割脉冲在初始啁啾为1.7 rad/s,色散长度0.64 m,非线性长度1.53 m时1 m长的光纤中的脉冲演化过程。结果表明,其色散感应脉冲展宽的定性特征与高斯脉冲近似一致,但色散感应的频率啁啾沿脉冲不再是纯线性变化,若输入脉冲峰值功率过大,会引起频谱振荡。

The transmission characteristics of Gaussian pulses in optical fiber has been solved by analytical solutions, but that of hyperbolic secant pulses emitted by mode-locked laser only depend on numerical methods. In order to study the transmission characteristics of hyperbolic secant pulse with high-power in a single-mode optical fiber, the split-step Fourier method was used to analysis the transmission procedure of the hyperbolic secant pulse in single mode fiber with initial chirp 1.7 rad/s, dispersion length 0.64 m, nonlinear length 1.53 m and length 1 m. The results indicate that the dispersion inductive spread of the hyperbolic secant pulse is consistent with the Gauss pulse, but its dispersion inductive frequency chirp is not vary linearly. It will also arouse the spectral oscillation if the input power is too high.